But the science is not there yet, experts cautioned.
"This is an important study looking at bacteria in the intestine and how they are related to BMI," said Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City. "The more methane and hydrogen in the breath, the higher the body fat." But, "we need more studies to figure out how bacteria is related to the growing obesity epidemic and what happens if we modify it," Mezitis said.
It's way too soon to start thinking about probiotics as a treatment for obesity, said Dr. Peter Green, director of the Celiac Disease Center at Columbia University Medical Center, in New York City. Green routinely uses breath testing to assess individuals with gastrointestinal issues such as bloating, diarrhea and constipation. "Some people with bacterial overgrowth in their gut have symptoms, but others do not and we are not sure why. The significance of the test results is not always quite clear," he said.
"More research is needed to really define the role of bacterial overgrowth in all of these different conditions," Green said. "It is an exciting area of research, but testing breath to measure body fat is not ready for prime time."
Another expert discussed implications of the new research.
This study adds to the growing evidence that breath tests can provide information about our health, said Dr. Raed Dweik, a pulmonologist at the Cleveland Clinic. "The argument that the authors make is that if we change the bacteria in the gut, we may change obesity and these people will not gain weight as easily," he said. "If we modify the bacteria in the gut, they may lose weight faster or easier."
The next step is to figure out how, or even if, this is possible, said Dweik, who on March 25 had his own study published on the use of breath testing to uncover heart disease risk.